Pressure rheostat



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UNITED STATES PATENT GFFICE PRESSURE RHEOSTAT Richard Garey, Brooklyn,N. Y.

Application July 23, 1949, Serial No. 106,399

9 Claims. 1

This invention relates to rheostats such as are commonly employed incontrolling operation of an electric sewing machine and similarapparatus. More particularly, the invention deals with a foot actuateddevice of the type and kind employing carbon disc resistors and a footactuated element for controlling operation of the rheostat.

The novel features of the invention will be best understood from thefollowing description, when taken together with the accompanyingdrawing, in which certain embodiments of the invention are disclosedand, in which, the separate parts are designated by suitable referencecharacters in each of the views and, in which:

Fig. 1 is a longitudinal section through a rheostat made according to myinvention.

Fig. 2 is a view similar to Fig. 1 showing one end portion only of thedevice with part of the construction in elevation and showing a sectionthrough a different part of the device.

Fig. 3 is a perspective plan view of the device.

Fig. 4 is a bottom plan view of the device, as seen in Fig. 1, with thecover and supporting ring removed.

Fig. 5 is a diagrammatic view of the circuit as shown in Figs. 1 4,inclusive, and;

Fig. 6 is a view similar to Fig. 5 showing a modification.

AIn practice, I employ an elongated shallow casing Ill which can beformed from moulded plastics or the like, the casing having an inclinedtop wall portion I at one end thereof, apertured, as seen at I2, andadjacent and at one side of the aperture I2, the wall II has a roughedtread portion I3 forming a foot-rest.

The deep end wall I4 of the casing is apertured, as seen at I5, for thereception of the circuit wires and all of thewalls of the casingterminate in an outwardly extending peripheral flange I6.

Mounted upon the inner surface of the top wall I1 of the casing are twoporcelain or other blocks I8 and I9, these blocks being held togetherand on the wall I1 by screws 20 and 2|. The blocks |8 and |9 are furtherheld in an assembled relationship to each other by the center bolt 22.At each side of the blocks I8 and I9 and formed on adjacent surfacesthereof are elongated bores 23 and 24, in which are disposed carbon discresistors 25 and 26. have carbon ends or caps 21 and 28 which protrudethrough one end of the blocks I8 and I9, as clearly seen in Figs. 2 and4 of the drawing. The outer or lower surface of the block I9 has alongitudinal recess 29. in which is slidably These resistors mounted anelongated bar 30, which may be termed a switch or contact bar, this barhaving elongated apertures 3| and 32 for reception of the screws 20, 2|,respectively. The heads of the screws retain the bar 30 in position. Oneend of the bar has an offset contact portion 33 with a protrudingcontact element 34. The other end of the bar has an offset wide plateportion 35, at each side of which are L-shaped bearing portions 36, noteFigs. 2 and 4.

The wide plate portion has secured to the center thereof a springcontact plate 31, the yieldable ends of which are adapted to engage theends 21 and 28 in completing the circuit through the carbon discresistors.

Also arranged between the plate 35 and the ends of the blocks I8 and I9is a spring 38, which normally supports the switch bar 3Uv in theinoperative position shown in Figs. 1 and 4 of the drawing. The innersurface of the inclined wall portion II of the casing has a transverseV-trough 39, note Fig. 2. This trough forms a pivotal support forcontracted pivot ends of a foot actuated switch lever or element 4|. Theelement 4| is preferably in the form of a plastic casting having, at oneend, a raised hollow footpiece 42, the central portion of the elementhaving, at one side of the footpiece, an elongated passage 43 for thereception of a sleevelike member 44 fixed to the casing I0 or the wall Ithereof, the sleeve being adapted to receive a screw 45 having a largehead 46.

At either side of the aperture 43, the lower surface of the element 4|has curved bearing surfaces 41, against which the inner surface of thescrew head 46 or a bearing ring 48 thereon is adapted to operate insupporting the element 4| in the casing and in guiding swinging movementof said element. In other words, the surfaces 41 are on a radius swungfrom the pivotal axis of saidv element. The sides of the element 4I,beyond the surfaces 41, have downwardly extending lugs 49 reinforced byweb portions 50. The lugs 49 are adapted to engage the L-shaped bearingportions 36 in actuation of the rheostat.

The blocks I9 and I9 have, at the other ends of the carbon discresistors, screws 5I and 52. The screw 52 has an offset terminal portion53, with which one circuit wire is adapted to be connected, as seen at54, Fig. 5; whereas the other circuit wire 55 is connected with thescrew 2| completing the circuit to the bar 30. The screw ends 5|, 52support a bridging contact plate 56, thus placing these ends of thecarbon disc resistors in circuit with the wire 54.

Supported on the screw 52 is an offset spring contact element 51,disposed in such position as to be engaged by the contact 34 of the bar39 in snorting-out the carbon disc resistors.

Turning now to Fig. 6 of the drawing, here is shown a slightmodification, wherein terminal wires 54', 55 are directly connected withscrews or posts 5l and 52', both of which are substantially similar tothe post 5I, 52 and include 53 in- A two spring contact fingers, as at51 an stead of the single nger 51. With this construction, the screws5I', 52 are not electrically ccnnected as by the contact or wire 56.Otherwise the structure of Fig. 6 is the same as that shown in Figs.1-5, inclusive. 30' in Fig. 6 represents the bar element which includesa spring contac 31 similar to 31.

With the structure shown in Fig. 6, resistance takes place through thetwo carbon disc units in series, whereas in Fig. 5, the circuit is inmultiple.

Turning now to the casing le, corner portions of the casing have seatsor platforms, as at 59, 59', and 60, 6U', upon which a lower cover plateor bottom wall 6| is adapted to seat. The plate 6l nts within the loweropen end of the casing and can be held in place by the inwardlyextending flange portion 62 of a rubber ring 63 or, if desired, thescrews can be passed through the plate and into une platiorm portions59, 55', one of these screws being seen at 64 in Fig. 1 of the drawing.The ring B3 envelopes the outwardly extending flange I6 of the casingand has an inturned lip engagement 65 therewith. The ring 63 ispreferably made of elastic material and can be extended to engage theflange portion of the casing in the manner shown. This ring also forms acushion support for the casing on any surface.

In the use of the device and when the parts are in normal position, asseen in Figs. 1 and 4, the spring contact 31 is out-of-engagement withthe ends 21, 28 of the carbon disc resistors and the element 4I, whichmay be regarded as a treadle, is in the raised position. However, uponapplying the foot to the element or the footpiece 42 thereof, theelement swings on its pivot end 40 and this operation moves the lugs 49into engagement with the bearings 3S which, in turn, advances the bar 30to the right, bringing the contact 31 into engagement with the ends 21and 28, thus completing the circuit and, as the element 4l is depressed,the resistance through the carbon discs varies in providing the desiredcontrol of machine operation. Upon depressing the element 4l to thefullest extent, the circuit is closed through the contacts 34, 51 orbetween the contacts 51', 58, Fig. 6, which, in both instances, willshort-out the resistance and provide direct current supply to theoperating motor.

With my improved construction, it will be seen that the element 4| is avery simple and economical construction and is held and guided in itspivotal mounting solely by the head of the screw or the bearing washerprovided thereon which operates over the arcuate surfaces 41. Thisswinging movement contributes to the switch bar 30, 30' the longitudinalsliding movement and a corresponding axial movement upon the carbon discresistors.

The lugs 49 are so positioned on the element 4I and, particularly, withrespect to the bearing portions 36 as to provide a more or less straightline action upon said bearings, thus minimizing frictional engagementbetween these parts. Suitable bushings 25', 2 I' are provided on thescrews 20, 2| for operation of the bar 30 thereon to again minimizefrictional engagement.

It will be understood that the two blocks I8 and I9 form a unit in whichthe carbon disc resistors and carbon pile resistors are arranged. Theswitch bar 3B may be said to comprise a carbon pile operating elementwhich is mounted on and movable longitudinally of said unit. It willalso be apparent that the footpiece or treadle element 4l has a freepivotal action in the casing and is held in the casing solely by thescrew 45. These structural features give simplicity to the end device.

From the foregoing, it will appear that the entire structure of thedevice is simple and economical which enables the device to be producedat a very nominal cost and, still further, the question of assemblage issimplified by reason of the simplicity in the structure.

Having fully described my invention, what I claim as new and desire tosecure by Letters Patent is:

l. A rheostat device of the character described comprising a casing openat the bottom, the casing being defined by top and side walls, the topwall having an inclined end portion, an insulated block unit secureddirectly to the inner surface of the top wall, said unit comprising apair of insulator plates secured together centrally thereof, two carbonpile resistors arranged and housed in the plates of said unit, anelongated bar mounted on and slidably engaging the lower surface of theblocl; of the unit, said resistors having terminal ends protrudingthrough one end of the unit, said bar having a cross-head in alinementwith said terminal ends, a spring contact supported on said cross-headfor yieldably engaging said terminal ends of the resistors, a manuallyactuated treadle pivotally mounted on the inner surface of the inclinedwall of said casing and having a footpiece protruding through andprojecting above the upper surrace of said wall. and said treadle andthe cross-head of the bar having cooperating members, whereby in manualoperation of the treadle the bar is moved longitudinally or' said unit.

z. A rheostat device of the character described comprising a casing openat the bottom, the casing being defined by top and side walls, the topwall having an inclined end portion, an insulated block` unit secureddirectly to the inner surface of the top wall, said unit comprising apair of insulator plates secured together centrally thereof, two carbon.pile resistors arranged and housed in the plates of said unit, anelongated bar mounted on and slidably engaging the lower surface of theblock of the unit, said resistors having terminal ends protrudingthrough one end of the unit, said bar having a cross-head in alinementwith said terminal ends, a spring contact supported on said cross-headfor yieldably engaging said terminal ends of the resistors, a manuallyactuated treadle pivotally mounted on the inner surface of the inclinedwall of said casing and having a footpiece protruding through andprojecting above the upper surface of said wall, said treadle and thecross-head of the bar having cooperating members, whereby in manualoperation of the treadle the bar is moved longitudinally of said unit,the other end portion of said unit having terminals with which circuitwires are connected, said terminals being in circuit with the carbonresistors, and means on said bar for aseaevs snorting-out the resistorsin one depressed position of said treadle.

3. A rheostat device of the character described comprising a casingopenat the bottom, the casing being dened by top and side walls, the topWall having an inclined end portion, an insulated block unit secureddirectly to the inner surface of the top wall, said unit comprising apair of insulator plates secured together centrally thereof, two carbonpile resistors arranged and housed in the plates of said unit, anelongated bar mounted on and slidably engaging the lower surface of theblock of the unit, said resistors having terminal ends protrudingthrough one end of the unit, said bar having a cross-head in alinementwith said terminal ends, a spring contact supported on said cross-headfor yieldablyengaging said terminal ends of the resistors, a manuallyactuated treadle pivotally mounted on the inner surface of the inclinedwall of said casing and having a footpiece protruding through andprojecting above the upper surface of said wall, said treadle and thecross-head of the bar having cooperating members, whereby in manualoperation of the treadle the bar is moved longitudinally of said unit,the other end portion of said unit having terminals with which circuitwires are connected, said terminals being irl circuit with the carbonresistors, means on said bar for shorting-out the resistors in onedepressed position of said treadle, and a single screw for supportingsaid treadle for free pivotal movement in the casing.

4. A rheostat device of the character described comprising a casing openat the bottom, the casing being defined by top and side walls, the topwall having an inclined end portion, an insulated block unit secureddirectly to the inner surface of the top Wall, said unit comprising apair of insulator plates secured together centrally thereof, two carbonpile resistors arranged and housed in the plates of said unit, anelongated bar mounted on and slidably engaging the lower surface of theblock of the unit, said resistors having terminal ends protrudingthrough one end of the unit, said bar having a cross-head in alinementwith said terminal ends, a spring contact supported on said cross-headfor yieldably engaging said terminal ends of the resistors, a manuallyactuated treadle pivotally mounted on the inner surface of the inclinedwall of said casing and having a footpiece protruding through andprojecting above the upper surface of said wall, said treadle and thecross-head of the bar having cooperating members, whereby in manualoperation of the treadle the bar is moved longitudinally of said unit,the other end portion of said unit having terminals with which circuitwires are connected, said terminals being in circuit with the carbonresistors, means on said bar for snorting-out the resistors in onedepressed position of said treadle. a single screw for supporting saidtreadle for free pivotal movement in the casing, and said treadle havingarcuate bearing surfaces operatively engaging said screw.

5. A rheostat device of the character described comprising a casing openat the bottom, the casing being defined by top and side walls, the topwall having an inclined end portion, an insulated block unit secureddirectly to the inner surface of the top wall, said unit comprising apair of insulator plates secured together centrally thereof, two carbonpile resistors arranged and housed in the plates of saidunit, anelongated bar. mounted on and slidably engaging the lower surface of theblock of the unit, said resistors having terminal ends protrudingthrough one end of the unit, said bar having a cross-head in alinementwith said terminal ends, a spring contact supported on said cross-headfor yieldably engaging said terminal ends of the resistors, a manuallyactuated treadle pivotally mounted on the inner surface of the inclinedwall of said casing and having a footpiece protruding through andprojecting above the upper surface of said wall, said treadle and thecross-head of the bar having cooperating members, whereby in manualoperation of the treadle the bar is moved longitudinally of said unit,the other end portion of said unit having terminals with which circuitwires are connected, said terminals being in circuit with the carbonresistors, means on said bar for snorting-out the resistors in onedepressed position of said treadle, and said last nam-ed meansoperatively engaging one of said terminals.

6. A rheostat device of the character described comprising a casing openat the bottom, the casing being defined by top and side walls, the topwall having an inclined end portion, an insulated block unit secureddirectly to the inner surface of the top wall, said unitcomprising apair of insulator plates secured together centrally thereof, two carbonpile resistors arranged and housed in the plates of said unit, anelongated bar mounted on and slidably engaging` the lower surface of theblock of the unit, said resistors having terminal ends protrudingthrough one end of the unit, said bar having a cross-head in alinementwith said terminal ends, a spring contact supported on said cross-headfor yieldably engaging said terminal ends of the resistors, a manuallyactuated treadle pivotally mounted on the inner surface of the inclinedwall of said casing and having a footpiece protruding through andprojecting above the upper surface of said wall, said treadle and thecross-head of the bar having cooperating members, whereby in manualoperation of the treadle the bar is moved longitudinally of said unit,the other end portion of said unit having terminals with which circuitwires are connected, said terminals being in circuit with the carbonresistors, means on said bar for snorting-out the resistors in onedepressed position of said treadle, and said last named melansoperatively engaging both of said termina s.

7. A rheo'stat device of the character described comprising a casingopen at the bottom, the casing being :defined by top and side walls, thetop wall havingan inclined end portion, an insulated block unit mountedupon the inner surface of the top wall, two carbon pile resistorsarranged and housed in said unit, an elongated bar mounted on andslidably engaging the lower surface of the block of the unit, saidresistors having terminal ends protruding through one end of the unit,said bar having-a cross-head in alinement with said terminal ends, aspring contact supported on said cross-head for yieldably engaging saidterminal ends of the resistors, a manually actuated treadle pivotallymounted on the inner surface oi the inclined wall of said casing andhaving a footpiece protruding through and projecting above the uppersurface of said wall, said treadle and the cross-head of the bar havingcooperating members, whereby in manual operation of the treadle the baris moved longitudinally of said unit, the other end portion of said unithaving terminals with which circuit wires are connected,

'andere said terminals being in circuit with the carbon resistors, meanson said bar for snorting-out the resistors in one depressed position ofsaid treadle, al single screw for supporting said treadle for freepivotal movement in the casing, said treadle having arcuate bearingsurfaces operatively engaging said screw, the lower portion of thecasing having atl corner portions thereof bearing suriac'es for aclosure plate, and means arranged on the" peripheral lower edge of thecasing for supporting said plate on the casing.

8. A rheostat device of the character described comprising acasing openat the bottom, the casing` being dened by top and side walls, the topwall. having an inclined end portion, an insulated block' unit mountedupon the inner surface of the top wall, two carbon pile resistorsarranged and housed in said unit, an elongated bar mounted onA andslidably engaging the lower surface of the block of the unit, saidresistors having terminal ends protruding through one end of the unit,said bar having a cross-head in alinement with said terminal ends, aspring contact supported on said cross-head for yieldably engaging saidterminal ends of the resistors, a manually actuated treadle pivotallymounted on the innerV surface of the inclined wall of said casing andhaving a footpieoe protruding through and projecting above the uppersurface of said wall, said treadle and the cross-head of the bar havingcooperating members, whereby in manual operation of the treadle the baris moved longitudnally of said unit, the other end portion of said unithaving terminals with which circuit wires are connected, said terminalsbeing in circuit with the carbon resistors, means on said bar forsnorting-out the resistors in one depressed position of said treadle, asingle screw for supportingsaid treadle for free pivotal movement in thecasing, said treadle having arcuate bearing surfaces operativelyengaging said screw, the lower edge portion of the casing having anoutwardly extending peripheral flange, a rubber ring engaging said ange,and said ring having an inwardly extending annular portion overlying thelower edge of the casing and the open end thereof.

9. In rheostat devices of the character described employing a pair ofcarbon disc resistors mounted in an insulated body and a switch elementcontrolling operation of said resistors, a. casing open at the bottomand having top and side Walls, said body being housed within the casingand secured to the top wall thereof, a treadle'y having a free pivotalmounting on the casing, the treadle having a part projecting outwardlythrough one wall of the casing for manual operation thereof, a singlescrew secured to the top wall of the casing for supporting the treadlein connection therewith, said switch element and treadle having pairs ofcooperating members at opposed sides of said screw for contributingmanual movement of the treadle to said switch element, said insulatedbody having a longitudinal groove on the lower surface thereof, theswitch element being mounted in said groove, and means on said bodyengaging the switch element to guide the same in its movementlongitudinally of said body.

RICHARD GAREY.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 1,777,988 Wilms Oct. 7, 19302,117,257 Shenk May l0, 1938 2,371,772 Naul Mar. 20, 1945

